[gdb/testsuite] Allow thread exited message in gdb.threads/infcall-from-bp-cond-simple.exp

With a gdb 15.2 based package and test-case
gdb.threads/infcall-from-bp-cond-simple.exp, I ran into:
...
Thread 2 "infcall-from-bp" hit Breakpoint 3, function_with_breakpoint () at \
  infcall-from-bp-cond-simple.c:51
51        return 1;     /* Nested breakpoint.  */
Error in testing condition for breakpoint 2:
The program being debugged stopped while in a function called from GDB.
Evaluation of the expression containing the function
(function_with_breakpoint) will be abandoned.
When the function is done executing, GDB will silently stop.
[Thread 0x7ffff73fe6c0 (LWP 951822) exited]
(gdb) FAIL: $exp: target_async=on: target_non_stop=on: \
  run_bp_cond_hits_breakpoint: continue
...

The test fails because it doesn't expect the "[Thread ... exited]" message.

I have tried to reproduce this test failure, both using 15.2 and current
trunk, but haven't managed.

Regardless, I think the message is harmless, so allow it to occur, both in
run_bp_cond_segfaults and run_bp_cond_hits_breakpoint.

Tested on x86_64-linux.

PR testsuite/32785
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32785
1 file changed